Method for preparing catalysts for preparing benzenetetracarboxylic anhydride

Abstract

The invention discloses a method for preparing catalysts for preparing benzenetetracarboxylic anhydride from durene by means of gas-phase catalytic oxidation. The catalysts comprise spray liquid and carriers. The spray liquid mainly comprises, by weight, 3-5 parts of ammonium metavanadate, 11.2-11.4 parts of oxalic acid, 0.2-0.4 part of diammonium hydrogen phosphate, 0.1-0.3 part of trisodium phosphate anhydrous, 0.18-0.2 part of antimony oxide, 1.1-1.3 parts of ammonium molybdate, 0.98-1 part of potassium hydroxide, 0.6-0.8 part of sodium dihydrogen phosphate, 0.18-0.2 part of potassium carbonate, 0.68-0.7 part of potassium dihydrogen phosphate, 1.16-1.18 parts of potassium phosphate and 8.6-8.8 parts of titanium dioxide powder; the carriers are 78.5-78.7 parts of porcelain rings. The method includes four steps of weighing, liquid preparing, spraying and calcining. The method has the advantages that the catalysts prepared by the aid of the method are good in activity, high in selectivity, low in hotspot reaction temperature and long in service life when applied, and partial energy consumption can be reduced when the catalysts are applied.

Description

technical field [0001] The invention belongs to the technical field of catalytic oxidation, in particular to a method for preparing a catalyst for preparing pyromellitic dianhydride. Background technique [0002] Pyromellitic dianhydride, referred to as homoanhydride or PMDA, is mainly used as a monomer of polyimide film heat-resistant resin, powder coating, matting agent, epoxy resin curing agent and plasticizer. Because PMDA has many excellent properties such as high temperature resistance, impact resistance and cryogenic resistance, the products made of it have been widely used in cutting-edge technology sectors, such as aircraft, aerospace, aviation, electronics industry and other fields. [0003] At present, domestic pyromellitic dianhydride production methods mostly use durene as raw material, vanadium-titanium series yellow catalyst as catalysis, gas phase oxidation method to produce crude product, referred to as crude anhydride, after hydrolysis, dehydration, sublima...

AI Technical Summary

Problems solved by technology

Since the oxidation process of homoanhydride production is a complex heterogeneous catalytic process, it consists of a series of reactions. The demethylation reaction of mesitylene will generate trimethylbenzene, mesitylene, o-xylene, benzene, etc., which will lead to homogeneous The crude anhydride product has low yield, poor quality, heavy color, less crystal particles, and more solid powder; at the same time, the catalyst used has a low weight gain rate and poor selectivity, and the equipment flow and operation process are complicated, and the operating cost is high